Image display devices such as cathode-ray tube (CRT) display devices, liquid crystal displays (LCDs), plasma display panels (PDPs), electroluminescence displays (ELDs), field emission displays (FEDs), touch panels, electronic paper, and tablet PCs are required to be provided with abrasion resistance in order to prevent damage during handling.
In response to such request, a hard coat film having a hard coat (HC) layer on a substrate film, and a hard coat film provided with optical functions such as anti-reflection properties and anti-glare properties have been usually used to improve the abrasion resistance of the image display surfaces of these image display devices.
It is preferred that the hardness of the hard coat layer surface of the hard coat film be higher for the purpose of improving the abrasion resistance of image display surfaces of image display devices. Various methods have been examined for increasing the hardness of the hard coat layer surface. For example, there is a method in which inorganic particles are incorporated in the hard coat layer. Patent Literature 1, for example, discloses such a hard coat film, wherein an intermediate layer formed by curing a composition containing a photocurable resin and a thermosetting resin is provided on a transparent substrate, and a hard coat layer is provided on the intermediate layer so as to improve the hardness.
However, in the case of conventional hard coat films, warping (curling) of the entire hard coat film and deflection of the film occur as the hardness of a hard coat layer is increased. Consequently, when such a hard coat film is affixed to a polarizing element or a display panel, air may be trapped, causing inclusion of air bubbles; or a film may be inwardly rolled, significantly impairing the processability.
Further, there has been demand for thinner films in order to reduce the weight of hard coat films. However, it has been impossible to sufficiently reduce the thickness of a hard coat film having an intermediate layer and a hard coat layer. Therefore, there has been demand to improve the hardness of a hard coat layer having a single-layered structure and decrease the film thickness of a transparent substrate. However, in the case of such a hard coat film having a hard coat layer of a single-layered structure and a thin transparent substrate, an attempt to increase the hardness of the hard coat layer has created problems such as curling and heat wrinkles.